Log debarking machine of the rotary scraper head type



April 5 F. DILLINGHAM 3,028,891

LOG DEBARKING MACHINE OF THE ROTARY SCRAPER HEAD TYPE Filed Aug. 27, 1959 INVENTOR F. L D/LL/NGHAM ATTORNEY6 HARDWOOD nit Patented Apr. 10, 1962 ace 3,928,891 1.06 DEBARKHNG MACHINE Di Tim ROTARY SCRAFER HEAD TYPE Frederick L. Diliingham, Sylacanga, Ala, assignor to Soderharnn Machine Manufacturing (30., Talladcga,

Ala.

Filed Aug. 27, 1959, Sier. No. 836,396 Claims. (Cl. 144-208) The present invention relates to the art of log debarking machines of the type capable of debarking logs of various sizes and hardness.

This invention is particularly related to that type of a log debarking machine which includes supporting means for a log to be debarkcd capable of rotating the log on its axis, a guideway extending parallel to the axis of a supported log, a carriage movable longitudinally along such guideway, and bark removing means carried by the carriage for operation on the supported logs.

Still more particularly, the invention relates to improvements in log debarking machines of the type disclosed in my prior filed US. patent application, Serial No. 808,367, filed April 23, 1959, and entitled Log Debarking Machine.

Specifically, this invention relates to an improved rotary scraper head for such a debarking machine.

In debarking machines of this type where the bark removing means are carried by a carriage that is capable of traversing a supported and rotating log from end to end, the debarking heads have incorporated chain llails, rotary cutters, and scraping mechanisms. That is, blades or vanes carried on a rotary drum for engagement with a log. Chain flails have a tendency to splinter the outer layer of the wood underlying the bark and thus cause waste, while cutter heads generally penetrate too deeply into the wood so as to likewise cause waste.

Therefore, the present invention relates to a debarking machine of the type described including a rotary scraper head, which separates the bark from the wood at the cambium layer within a minimum of waste and without causing undue damage to the wood layer.

Tree growth is both inwardly and outwardly from cambium layer, which lies just between the wood and the bark. The cambium layer is the natural surface of separation between the Wood and bark and advantage is taken of this in the present invention.

Some varieties of trees have bark that separate very easily from the wood, notably willow, in which the complete bark from short sticks can be often removed without even slitting the bark. Other varieties, especially of hard woods, are such, that it is much more difficult to separate the bark from the wood. In using the earlier known debarking heads, it has been found that great skill is required on the part of the operator to adjust the machine so as not to waste excessive wood, especially in the case of logs which are easy to debark.

Since it has been found, that logs very difiicult to debark require a slightly different conformation of the debarking head than do logs that are easy to debark, the present invention has for one object to provide a debarking head having two elfective bark engaging surfaces so that the head may be reversed in the debarking machine, in order that the debarking head surface or configuration which is most suitable to the hardness characteristic of logs being processed can be utilized.

In using the formerly known chain ilail debarkers, and the cutting debarkers, it was necessary to use rider bars or gauge devices in order to ensure that the flails or the cutters would not chew too deeply into the wood of the log itself. In the device of the present invention such rider bars or gauges are not required.

Therefore, the principal object of this invention is to the provide a head for a debarking machine that will separate the bark from the log at the cambium layer without waste.

It is a further object of the invention to provide a debarking head which does not require the use of rider bars.

It is a further object of the present invention to provide a debarking head for a debarking machine which is inexpensive in manufacture, and in maintenance, is efiicient in operation and is not wasteful of the wood lying below the cambium layer. Other and further objects and advantages will appear from the following specification taken with the accompanying drawing, in which like characters of reference define similar partsin the several views and in which:

- FIGURE 1 is a general perspective view of a debarking machine using the debarking head of the present invention,

FIGURE 2 is a view partly in section of the debarkin head,

FIGURE 3 is a diagrammatic section of the debarking head in operation,

FIGURE 4 is a fragmentary section through one rib of the tread of the debarking head.

The debarking machine illustrated in FIGURE 1 is of the type disclosed in my copending application, Serial No. 808,367 and includes a base carrying bull wheels 19 driven by a suitable drive means D in the direction of .the arrows so that a log 15 rotates in the opposite direction. Above and to one side of the supported log is a longitudinally extending guideway means 17, rockable about pivot means 18, incorporated with suitable uprights at opposite ends of the base. A carriage C is traversable along the longitudinal guideways 17, and this carriage includes a frame 16 in which is mounted a shaft 11 that in turn mounts a debarking head It}. The shaft 11 is driven by electric motor 12 through a belt transmission including belts 13 and 14 and an intermediate shaft also carried by the frame 16. Since the guideway and the carriage thereon can rock up and down about pivots 18, the debarking head can be placed in operative engagement with the log being debarked. The speciic structure and operation of the debarking machine is fully disclosed in said above-mentioned application.

The log 15 and the debarking head 10, as shown in FIGURES 1 and 3 rotate so that their adjacent surfaces are moving in the same direction with the head rotating faster than the log so that the bark-removing treads 21 have an appropriate speed with respect to the surface of a log.

In FIGURE 1, the debarking head 10 rotates in a clockwise direction and the log rotates in a counterclockwise direction. The debarking head 10 includes a cylindrical body or shell portion 20 carrying on its periphery a plurality of ridges or treads 21 of a particular configuration, which will be explained hereinafter.

The treads 21 may extend parallel to the axis of the body or drum 20, but are preferably arranged to extend helically. In one embodiment, in which the body of the drum 2%"; has a diameter of about twelve inches and is twelve inches long, the treads are provided with a six inch twist in the twelve inches of drum length, and eight treads are mounted on the drum by being welded thereto. be varied without departing from the scope of the invention.

The log 15 includes a central wooden portion 22 surrounded by a bark layer 23 which is separated from the wooden portion by the intervening cambium layer 24.

Thus, each tread of the debarking head as it approaches the log 15 first strikes the bark layer 23 with an impact toward the wood portion 22 and then passes tangentially of the circumference of the wood portion 22 which The number of treads and the amount of twist may is also the circumference of the cambiurn layer 24. In this connection, a circle that enscribes the outer surface of the treads 21 is tangent to the circumference of the central wood portion of a supported log. As each tread removes its portion of the bark, the log is turned so that the following tread strikes the outer surface of the bark and another piece of bark is removed. The outer surface and opposite end edges of the treads are blunt. Therefore, the treads do not dig into the wood layer and the bark is readily removed. The debarlcing head will be traversed lengthwise of the log and since the ends of the treads move tangentially to the cambium layer the debarking ead does not require rider bars as were necessary in embodiments utilizing chain flails and cutters.

The operation of the debarking machine is the same as set forth in my above-mentioned prior filed application.

FIGURE 2 illustrates in more detail the construction of the debarldng head. The shaft 11 is carried in suitable journals or bearings provided on the opposite arms of the rock frame 16. The debarking head includes the drum portion and two end discs and 27. Between the two outer or journalling portions of shaft 11, the shaft is enlarged, and adjacent one journal there is a peripheral groove 11'. The end disc 25 is provided with an internal hub 25', which is keyed to the enlarged portion of shaft 11 by a key 26. A spacer 251 is interposed between the outer face of disc 25 and a snap ring 261, which is accommodated in the groove 11. The peripheral edges of both discs 25 and 27 are bevelled at an approximately 45 angle as shown at 28 and 29. The opposite ends of the drum 2t) are correspondingly bevelled so that after one bevelled end of the drum is placed against the bevelled edge 28 of disc 25, the other end disc 27 can be mounted on the shaft to bear against the opposite end of the drum. The end disc 27 also includes an internal hub that is slidably keyed to shaft 11.

In order to clamp the discs 25 and 27 against the ends of drum 20 locl; nuts 30 and 31 are threaded on an externally threaded portion 32 of shaft 11, so that the drum is held between the discs by friction and it is centered by the cooperation of the bevelled edges of the discs with the bevelled ends of the drum.

With the arrangement just described, by removing the shaft bearings from the box frame 16, the connection of the drum shaft 11 can be disassembled by removing the lock nuts 30 and 31 then withdrawing disc 27. Fol lowing this, the drum can be withdrawn and reversed, whereupon the clamping disc 27 can be again mounted on the shaft and clamped against the end of the drum. The purpose of reversing the position of the drum on the shaft 11 is to utilize the shape and configuration of the debarking treads 21 in a most efficacious manner.

As shown in FIGURE 4, these treads have opposite side faces 33, and are of generally trapezoidal shape, the largest base of which forms a chord between the points of intersections of the two side faces with the cylindrical surface of the drum 29. The two side faces of the treads are not at the same angle with respect to a radial plane through the drum that passes through a point at the intersection of the plane containing faces 33 and 35. The outer surface 34 of the tread is preferably formed so as to be a cylindrical surface of the same radius as its distance from the center of the shaft 11. If desired, this outer face may be flat. One face 35 of the tread forms an acute angle of with said radial plane through the drum, or an angle of 135 with respect to a tangent to the surface of the drum. The other face 33 forms an acute angle of 20 with such radial plane or of 110 with respect to a tangent of the surface of the drum 20. While these two angles may be varied, it has been ascertained in practice that the particular angles mentioned give highly satisfactory results. The face 35 is utilized as the active bark-removing face when debarking softwoods. Thus, with respect to FIGURE 4, the drum 29 would rotate coun erclockwise as shown by the arrow labeled Softwood. The face 33 of the treads constitutes the operative faces when debarking hardwoods and thus with reference to FIGURE 4, the drum would be rotated in a clockwise direction as shown by the arrow labeled Hardwood.

FIGURES l and 3 show an arrangement in which the drum 2% is so mounted on the shaft 11 that in operation the faces 35 of the treads are the leading faces as regards the direction of rotation, so that the log being debarlted is predominantly softwood. If the logs that are to be dcbarlted thereafter are prctioninantly of hardwoods, the drum 20 is reversed as regards its relationship between the discs 25 and 27, so that the face 33 of each tread 21 is the leading face.

it is clear, therefore, that the invention contemplates a debarking head structure for a debarking machine and consists of a rotary drum having treads formed on the periphery thereof, the treads having leading and trailing faces as regards the direction of rotation of the drum, which are inclined at different angles with respect to a radial plane that passes through the treads and also passes through a point at the intersection of the planes containing said faces, whereby the drum may be reversed from end to end to selectively engage either face of each tread with a log to be dcbarked depending upon the hardness characteristic of the wood. It is further pointed out that the bearings that support the shaft 11 are removably mounted on the frame 16 so as to facilitate disassociation of the shaft and drum carried thereon from the frame 16 to permit removal of the nuts 30, 31 together with end disc 27 for reversal of the drum 20.

It is believed clear that the shaft 11 could be driven for rotation in opposite directions, particularly if the treads were parallel to the axis of the drum so that by supporting the log on a frame or table wherein the logs could be reversely rotated as desired, the operator could adapt the machine to debarking hardwood or softwood by merely controlling the direction of rotation of the log and the debarking head.

It is believed clear that the details of construction embodied in the drawings may be altered without departing from the scope of the invention as set forth in the following claims:

What is claimed is:

1. In a debarlting machine of the type including means for supporting and rotating a log about its axis, a carriage movable in opposite directions along a path parallel to a supported log and alongside the same, a debarking means carried by the carriage for debarking a supported log and means for raising and lowering the carriage and thus the debarking means relative to a supported log, said debarlting means comprising a rotary shaft carried by the carriage and extending longitudinally of a supported log, a reversible drum means removably carried by the shaft and having a cylindrical body portion, a plurality of treads extending outwardly from the periphery of the drum means, spaced around the drum means and extending longitudinally thereof, said treads having opposite faces extending between the surface of the drum means and the tip and with respect to each tread lying at different angles with respect to a radial plane passing through the drum means at the tip and through a point of intersection of the planes containing said faces, said angles being selected so that one face of the tread is operative to dcbarl; hardwoods, whereas the other face of the tread is operative to debark softwoods.

2. A debarlring means as claimed in claim 1 in which the face on one side of each tread lies at an angle of approximately 45 to the said radial plane and the opposite face of each tread lies at an angle of approximately 20 with respect to said radial plane.

3. A rotary dcbarking means for a debarlring machine comprising a rotary shaft, reversible drum means removably carried by the shaft including a cylindrical body portion, a plurality of bark-removing treads carried by the body portion, spaced around the same and extending generally longitudinally thereof each tread including opposite faces and a tip, the tips having their outer surfaces and opposed end edges blunt so as to readily re move bark without digging into the-underlying-wood layer, and means mounting the drum means on the shaft including beveled ends on the body portion of the drum and complementary beveled disk members removably secured to the shaft so as to permit endwise reversal of the body portion of the drum between said disk members in order to select which face of the treads is to engage a log to be debarked.

4. A rotary debarking head for a debarking machine comprising a cylindrical body portion, a plurality of ridges on said body portion extending generally axially thereof, each ridge being of generally trapezoidal section including opposite faces and with its longer base forming a chord between the points of intersection of said faces with said cylindrical body portion, one face of each ridge lying at an angle of approximately 45 to a radial plane passing through the drum at the ridge and a point of intersection of the plane containing said one face, and each ridge having a tip having its outer surface and opposed end edges blunt so as to remove bark without damaging the wood layer.

5. The debarking head of claim 4 in which the other face of each ridge lies at an angle of approximately 20 with respect to said radial plane at said point of intersection.

6. A rotary debarking head for a debarking machine comprising a cylindrical body portion, a plurality of ridges on said body portion extending generally longitudinally thereof and spaced therearound, said ridges being of generally trapezoidal section and having pposite angular faces, the larger base of each ridge lying on a chord joining the points of intersection of said faces with said cylindrical body portion, and each ridge having a tip having its outer surface and opposed end edges blunt so as to remove bark without damaging the wood section of the planes containing said faces are 45 and i 20 respectively. a

8. A rotary debarking means for a log debarking machine comprising a rotary shaft adapted to be mounted to extend longitudinally of a log, a first end disc keyed to said shaft means holding said disk againstmovement longitudinally of the shaft in one direction, a cylindrical drum surrounding the shaft and having its outer diameter of approximately the same diameter as the diameter of the disc, a second disc and similar slidably keyed on said shaft for engaging the opposite end of the drum, means removably carried by the shaft and adjustable therealong in said one direction for clamping the second disc against the drum and thus clamping the drum between the discs, and blunt-tipped bark-removing treads carried by the periphery of the drum.

9. A rotary debarking means as claimed in claim 8 and said treads having opposite faces and a tip, the faces on one side of the treads extending at an angle to a radial plane through the drum that passes through the tip and a point of intersection of the planes containing said faces that is effective to debark hardwoods and the opposite faces of the treads extending at a different angle to such radial plane as to be effective to debark softwoods.

10. A rotary debarking means as claimed in claim 8 and the respective discs and opposite ends of the drum being cooperatively beveled so that the clamping of the drum between the disc also centers the drum.

References Cited in the file of this patent UNITED STATES PATENTS 451,118 Evans Apr. 28, 1891 650,924 Boynton June 5, 1900 1,019,564 Unterloif Mar. 5, 1912 1,149,304 Taggart Aug. 10, 1915 1,358,533 Elston Nov. 9, 1920 1,728,570 Lagus Sept. 17, 1929 1,735,594 Anderson Nov. 12, 1929 1,995,290 Bazzoni Mar. 26, 1935 2,034,908 Kirkwood Mar. 24, 1936 2,305,281 Taylor et a1. Dec. 15,- 19 2 2,902,070 Latimer Sept. 1, 1959 FOREIGN PATENTS 222,569 Germany Jan. 19, 1901 

